Vehicle power transmission system



Sept. 2, 1952 u. F. LUEBBEN VEHICLE POWER TRANSMISSION SYSTEM FiledJlily 14, 1949 6 Sheets-Sheet J Jnuznfor Z7. 5. 2. zze'bbzn W Mama:

Sept. 2, 1952 u. F: LUEBBEN VEHICLE POWER TRANSMISSION SYSTEM 6Sheets-Sheet 2 Filed July 14, 1949 .mN m OWN Sept. 2, 95 u. F. LUEBBEN2,608,333

VEHICLE POWER ynsuxssro; SYSTEM Filed July 14, 1949 s Sheets-Sheet 4IIIIIIIIIIIIIIIII/IIIIIIIIII (III I 2 B5 6 4 5 mm Sept. 2, 1952 .u. F.LUEBBEN VEHICLE POWER TRANSMISSION SYSTEM 6 Sheets-Sheet 5 Filed July14, 1949 426 Jnz/znioz U. 2 Zzurbben 2; f

m9 2 u 7 B Kn M0235 p 2, 1952 u. F. LUEBBEN 2,608,833

VEHICLE POWER TRANSMISSION SYSTEM Filed July 14, 1949 6 Sheets-Sheet 6im/mzi'or D: i ,L uzbbe'n iatcnted Sept. 2, 1952 UNITED STATES PATENT 7OFFICE 2,608,883 VEHICLE PGWER' TRANSMISSION SYSTEM Uinmo EiLucbben,Omaha; Nebr. I Application July 14, 1949, SerialNo. 104,763

Claims. 1 I

This invention relates generally to a vehicle power transmission systemand in particular to acombination power transmission; and steeringsystem for a three-wheel farm tractor havinga pair of oppositelyarranged traction wheels and a castor or swiveled ground-engaging wheelspaced from the tractor wheels longitudinally of the tractor.

Farm tractors now in common use, although generally satisfactory inoperation, have been found to be objectionable in certainrespects. Oneof these objections results from the usual front wheel steerin systemwhich necessitates a relatively large turning radius for the tractor.This requirement is particularly objectionable for work on row crops orin close, quarters. Further objection arises because of the locationofthe usual tractor seat above the tractor'rear axle-and rearwardly ofthe tractor engine. Since farm implements are either drawnby'the'tra'ctor, supported nearlthe front end of the. tractor, orcarried on the tractor at a position behind the rear axle, the tractoroperator can observe the action of the implement only by' maneuveringinto a position to look forwardly and down along one side of thetractor, or by frequently-turning around and then looking down. Either'ofth'ese conditions is fatiguing and inconvenient to the tractoroperator. Further, followinga row or a line of an irregular contour,difficulties are-encountered due to the fact that the path followed I bythe implement is not directly responsive to the steeringof the tractor.Inother words, compensation in the steering of the tractor must be madein an effort to have the implement" follow a predetermined path.

It is an object of this invention, therefore, to provide an improvedfarm tractorin which an implement carried by'the tractor is in full'viewof the tractor operator and steerable directly in response to a steeringmovem'entof'the tractor;

Another object of thisinvention isto provide a combination powertransmission andsteering system for a three-wheel farm tractorcapable ofoperating the tractor in reverse directions at varying speeds, ofturning the tractor through a ment carried'thereon is controlled as, aself-- propelled unit. a

Another objector this invention: is to providea power transmissionsystem for a. three-wheel tractor having a pair" .of..opposite1yarranged traction wheelsand a free swiveling castor: wheel, in which thetraction wheels-are. independently driven and" capable of being drivenatthe same speed; or relative speeds, in: either aforward or.

reverse direction, and with variations; in speed ordirection being.accomplished without the, use of any dii ferenti'a'l or clutch:mechanism..

Still a further object of this invention is to provide apowertransmission device: forzatractor having a pair-of traction wheelsi'nlwhich'a tractor brake-means isassociated.1with..the transmis.- sion'system such that on. actuation of. anindividual foot brake meansfor'each traction swheel, power to the wheel corresponding tothe-actuated foot brakeis cut off as :thexbraking: of suchwheel isinitiated whereby.- to eliminate: any stalling; of; the tractor motor or:anydamage to the; trans.- mission system as a result: of the. sudden.W121ication of the brake.

Yet anotherobject of this inventionisto provide a tractor in which a.powertransmission system for the traction wheels is. of:a. simpler andrugged construction, immediately: and directly responsive to the controlof: the; operator 170711131- neuverthe tractor for steeringmeyersingorspeed changes, and in which changes-in the operation of the tractorcan be madeaqnickly and smoothly and with complete safetyto the" tractorand to the tractor operator..

A feature of this invention: issifound in the Provision of a powertransmissionsystem 0i friction type for. a vehicle having: a pairyofOppQSitely arranged traction wheels, .in which .a; power shaft isequipped with a pair of. spaced friction? discs. A pair of drive shafts,normal tothe powershaft and arranged between the frictiondiscswarez'independently connected with a corresponding traction Wheel.Each drive shaft. carries an axially movable friction wheel which isfrictionally engageable with one or-the other of the friction discs:Further, the driveshafts are movable axially of the power shaft tofriction-ally one another axially of their respective drive shafts tovary the speed of rotation of the traction wheels for tractor speedchange and steering purposes in either a forward or reverse travel ofthe tractor.

A further feature of this invention is found in the provision of a powertransmission system of friction type for a three-wheel farm tractorhaving a pair of oppositely arranged traction wheels and aground-engaging castor wheel, in which a power shaft has a pair of fixedfriction discs operatively associated with a pair of movably supportedfriction wheels, adapted to be frictionally engaged with one or theother of the friction discs, and independently connected with acorresponding traction wheel. An actuating unit for moving the frictionwheels to positions providing for a reverse, and forward travel of thetractor, and to a neutral position in which the friction wheels are outof frictional engagement with the friction discs, is of an overcenter ortoggle action type and is connected with the friction wheels throughmeans including a spring connection'so that the friction wheels are heldagainst the discs with equal pressure.

Yet another feature of this invention is found in the provisionof apower transmission system for a tractor, which is readily adjustable toprovide for the operation of the tractor in a reversed direction withall of the facility and ease of maneuverability of a forward directionof operation.

Further objects, features an advantages of this invention will becomeapparent from the following description when taken in connection withthe accompanying drawings, in which:

Fig. l is a foreshortened side elevational view of a tractor showing thecombination power transmission and steering system of this invention inassembly relation therewith, with certain parts being broken away andothers being shown in section for the purpose of clarity;

Fig. 2 is a plan view of the assembly shown in Fig. 1;

Fig. 3 is an enlarged plan view of the power transmission and steeringsystem taken substantially along the line 33 in Fig. l, with certainparts being broken away to more clearly show its construction;

Fig. 4 is a sectional view taken substantially along the line 4-4 inFig. 3;

Fig. 5 is afragmentary foreshortened detail perspective view showing theactuating means for operating the steering and speed-change mechanismsin the system of this invention;

Fig. 6 is a plan view, illustrated similarly to to Fig. 3, but havingcertain parts removed and other parts added so as to more specificallyshow only the speed change and the steering mechanisms embodied in thetransmission system of this invention;

Fig. '7 is a sectional detail view taken along the line 1-1 in Fig. 5;

Fig. 8 is an enlarged sectional detail view as seen along the line 8-43in Fig. 6;

Fig. 9 is a fragmentary perspective detail view of that part of thesystem of this invention which provides for the braking of the tractortraction wheels;

Fig. 10 is a plan view illustrated similarly to Fig. 3, but havingcertain parts removed so as to more specifically show the mechanismembodied in the system of this invention which provides for the turningmovement of the tractor within a space defined by the distance betweenthe traction wheels of the tractor;

. assembly;

Fig. 16 is a sectional detail view as seen along the line 16-46 in Fig.10 or Fig. 14; and

Fig. 17 is an enlarged sectional view taken on line ll-H in Fig. 2 andshowing a part of the braking mechanism.

With reference to the-drawings the combination power transmission andsteering system of this invention is shown in Figs. 1 and 2 in assemblyrelation with a three-wheel farmtractor having a main frame, designatedgenerally at 20, comprised of a pair of longitudinal frame members 21and 22, front and rear transverse members 23 and 24, respectively, and apair of intermediate transverse members 26 and 21. Supported from thelongitudinal frame members, at positions over the front end portionsthereof, are sub-frame structures 28 for independently carrying wheelaxles 29. Mounted on the axles 29 are a pair of oppositely arrangedtraction wheels 3| and 3la which support the front end of the main frame20.

The rear end of the main frame is supported by a ground-engaging castorwheel 32 which is pivotally mounted in a bracket 33 secured to the reartransverse frame member 24 as by bolts 34 inserted through selected onesof a series of holes 36 formed in the'transverse member 24. In otherwords, the castor wheel is adjustably secured at any position over thecomplete length of the rear transverse member 24, depending upon thefarming operation to be performed by the tractor.

Mounted on each wheel axle 29, inwardly of a corresponding tractionwheel 3| and 3m are sprocket gears 31 and 31a which are connectedthrough chains 38 and 38a with sprocket gears 39 and 39a fixed on stubshafts 4i and am. The stub shafts 4i and 41a are supported from thelongitudinal frame members 2| and 22, respectively, at positionsrearwardly of their associated wheel axles 29. Second gears 42 and 42a.on the stub-shafts 4| and 4m are connected through chains 43 and 43awith sprocket gears 44 and 44a mounted on drive shafts 46 and 46a. Thedrive shafts 46 and 46a form part of the power transmission system ofthis invention, which will now be described.

This system,.indicated generally at 45 in Figs. 1 and 2, includes ahousing 41' of a substantially square-box shape having an open bottomand a top closed by a cover member 48 provided with a seat 49 for thetractor operator. The supporting frame for the housing comprises uprightcorner members 5L of an angle iron construction secured at their lowerends to the intermediate transverse members 26 and 21. These uprightcorner members 51,.adjacent their top ends, are connected together bytransversely extended tubular members 52 and, 52a and longitudinallyextended angle members 53. Intermediate their ends the upright angles 5|are connected together by longitudinal brace memaeosgsesbers '4 andtransverse members 56 and 56m (Figs. 1 and 4) A power shaft 51 (Figs. 1,2- and 3), arranged longitudinally of the tractor, extends throughthehousing M and is rotatably supported in bearings 58 mounted on thebrace members 56 and 56a. Power to the shaft 51 is supplied; from anengine 59, a fuel tank for which is indicated at 6!. The engine 59 andtank BI are carried adjacent the rear end of the frame 20 and theengine, shaft is equipped with pulleys 62 which are connectedwithpulleys 63 on the power shaft 57 through. V-belts 64.

Arranged within the housing 41 (Fig. 3) and mounted on the. power shaft51 are a pair of spaced friction discs 6.5. and 66a having theirfriction surfaces faced toward, each other. The drive shafts 46 and 46aare arranged inco-axial alignment between the friction discs 6'6 and 66aand at opposite sides of the power shaft 51. .The shafts 46 and 460. arein a plane parallel with the friction discs 56 and 65a so as to be atright angles to the power shaft 51. Each shaft 46 and 46a (Figs. 1 and2) has its outer end rotatably supported in a bearing 51 which iscarried at the top of an upright standard 68 secured to a longitudinalframe member 2| and 22.. shafts 46 and 46a (Figs. 3 and 4) projectWithin the' housing 4'! from opposite sides thereof and have their inneradjacent ends rotatably supported in self-aligning bearings H and 1 la(Figs. 3 and 9) which are suitably secured to a pair of oppositelyarranged upright pivot arms 12 and 12a. The arms 12 and 12a are arrangedat opposite sides of the power-shaft 51 and have their lower endspivoted on a common pin t5 which is carried in a tubular support 14extended axially of the power shaft 51 at a position spaced therebelow,and connected between the intermediate transverse members 26 and2l ofthe main tractor frame 29. It is seen, therefore, that the axes of thepower shaft 51 and drive shafts 45 and 46d are arranged in asubstantially common horizontal plane, and with the power shaft 51.extended at right angles between the inner-adjacent ends of the driveshafts 46 and 45a.

Mounted on the drive shafts 45 and 45a. for rotation therewith, but foraxial movement relative thereto, at positions spaced outwardly from thebearing members H and lid, are hub units and 'lfla- (Fig. 3) which inturn carry friction wheels 13 and 13a. These friction wheels '53 and 13aare of a diameter substantially equal to the diameter of the frictiondiscs 6% and 66a.- and have a peripheral friction surface adapted forfrictional engagement with the frictional face or side. surfaces of thefriction discs 66 and 66a. It is contemplated that the friction discs 66and 55a be spaced a distance apart such that the overall workingclearance of a friction wheel i3 and 13a with the discs is in theneighborhood of about of an inch, when a friction wheel is in a neutral0r centrally located position between the friction discs. Since power istransmitted to drive shafts 46 and Mia as a result of the frictionalengagement of its associated friction wheel with one or the other of thefriction discs 66 and 66a, it is seen that each drive shaft is operatedindependently of the other drive shaft, and with the direction ofrotation and speed of rotation of a drive shaft being dependent on therelation of its corresponding friction wheel with a friction discs 66and 66a.

The presentiinvention provides for the operation of the friction wheels13 and 13a in a com- The drive p leiner-itary relation with the frictiondiscs 66: and 66a to achieve a complete maneuverability of the tractor.This operation includes a concurrent movement of the friction wheels 13and 13a. to either advance or reverse the tractor without changing thespeed of travel of the tractor; a movement of the'friction' wheelsrelative to the friction discs to either increase or decrease the speedof travel of the tractor-in either a forward or reverse directiontherefor; a movement of the friction wheels to relatively vary the speedof rotation of thedrive shafts 4B and 46a to steer the tractor; africtional disengagement of one of the, friction wheels from a frictiondisc 65 or 66a while maintaining the other friction wheel in engagementwith a friction disc, to accomplish a sharp turning movement of thetractor about one of the traction wheels 3| or 3 la; and a movement ofthefriction wheels 13 and 13a into frictional engagement with a singleone of the friction discs 66 or 65a to provide for a reversed relativerotation of the drive shafts and 46a and a resultant turning movement ofthe tractor about a center point located substantially between theinner-adjacent ends of the drive shafts 46, and 45a, namely, within aturning radius defined by one-half the distance between thetractionwheels 31 and am. For the purpose of convenience, the mechanismsembodied in the power system of this invention for operating thefriction 'wheelsdt andlta, to provide various tractor operations will beseparately described.

Mechanism for advancing and reversing tractor With reference to Figs. 3and 10, the front upper connecting member 52- between the upright cornermembers 5! is provided intermediate its ends with a pair of transverselyspaced rearwardly extended supporting plates 81 and am, the front endsof which are secured, as by welding, to the front connecting member 52.In other words; the plate supports 8-] and Sid project withinothehousing between the friction wheels 13 and 13a. Located between thesupporting plates BI and fila with its front end 82 loosely resting onthe front-connecting member 52 is a shiftable bar 83 (see also Fig. 11).The rear end84 of the shiftable bar 83 rests on the rear connectingmember 52a and is formed with a notch 86 for loosely receiving anupright guide pin 81 on the connecting member 52s. It is thus seenthat'the shiftable bar 83 is movable axially of the power shaft 57 andis arranged in a ver tically spaced position above the power shaft, soas to be between the inner-adjacent ends of the drive shafts 46 and 46a.Y

Carried intermediate the ends of the shiftable bar 83 is, an uprightpivot 83 for a T-shape lever 89. The pivot 88 is located intermediatethe ends of the cross-arm 9! of the T-lever 89, with the legSZ of suchT-member extended rearwardly in substantial longitudinal alignment withthe shiftable bar 83. The opposite ends of the cross arm 9| arepivotally connected at 93 and 93a (Figs. 9 and 10) with outwardlyextended lateral projections 94 and 94a formed at the upper ends of theupright pivoted arms i2- and file.

The actuation of the T-member 89 to move the friction wheels it and 13ain relatively reversed directions axially of the power shaft El isaccomplished by means including a shift lever ported on the top ends ofthe upright corner members 5!, of the housing 41, and at a positionspaced upwardly from the connecting members 52 and 52a and 53 is a topframe of an angle iron construction, indicated generally as I I It isthis frame IOI which carries the housing cover 48 and provides for afree longitudinal movement of the shiftable bar 83 on the top sides ofthe connecting members 52 and 52a.

The shift lever 96 (Figs. 10 and 16) includes a pin or shaft I02rotatably supported in an upright sleeve bearing I03 carried on theframe IOI at the right hand side of the tractor. A horizontal arm I04secured to the upper end of the pin I02 is equipped with a hand knobI06. Mounted on the lower end of the pin I02 is a second arm IGI, thefree end of which carries a pin I08 which projects downwardly throughone end I05 of a tubular spring casing I09.

Inserted through the opposite end H2 of the casing I09 is a bolt H3(Fig. 14). A coil spring H4 mounted about the bolt H3 is arrangedbetween collars H6 and III loosely carried on the bolt, with the collarIII at the inner end of the bolt H3 being engageable with stop screws H8and the collar H6 near the outer end of the bolt H3 being engageablewith stop screws H9, with the screws H8 and H9 being threadable throughthe casing I09 so as to project inwardly thereof. A spacer sleeve I2I,integral with the collar I I6, and projected outwardly from the easingend I I2, is adapted for abutting engagement with an adjusting nut I22.Threadable on the outer end of the bolt I I3 is a rod I23, whichconstitutes an adjustable extension for the bolt H3 and is held in anadjusted position by a lock nut I25.

The free end of the extension I23 is pivoted at I24 to one arm I26 ofthe bell crank 98 with the arm I26 being of an arcuate shape (Fig. Thebell crank 98 is pivoted at I2I on the connecting member 52a and itssecond arm I26 is pivoted at I29 to one end of the pivoted lever 99. Theopposite end of the lever 99 is pivoted at I32 to the free end of theleg 92 of the T-member 89. The assembly of the bolt H3, bell crank 98,pivoted lever 90 and T-member 89 is such that all of these members aremovable in a substantially common horizontal plane.

As shown in Fig. 10, the forward and reverse shifting mechanism, abovedescribed, is in its neutral position at which both of the frictionwheels I3 and 13a are out of frictional engagement with the discs 66 and66a. At this neutral position, the shift lever 96 extends axially of thedrive shaft 46a with its hand knob I06 to the outside of the top frameIt". Further, in a neutral position of the shift lever 96, and referringto Fig. 14, the collars H6 and H1 are in contact engagement with theirrespective stop screws H9 and H8, so that the spring H4 is extended toits fullest length. As a result, any tendency of the friction wheels I3and 13a to move out of their neutral positions is resisted in eitherdirection by the spring H4 so that the friction wheels are yieldablyheld in their neutral or disengaged positions relative to the frictiondiscs 66 and 66a.

To provide for a forward advance of the tractor, and assuming thedirection of rotation of the power shaft 51 to be counterclockwise whenviewed from the front of the tractor, the shift lever 96 is movedforwardly from its position shown in Figs. 10 and 14 to its stopposition shown in Figs. 3 and 13, as defined by the engagement of armI0I-wfth the stop 95. At this forward position of the shift lever 96 thepivot I08 is moved off center relative to the shaft I02 whereby toyieldably lock the shift lever 96 against movement toward its neutralposition. On this movement of the shift lever 96 to its forwardposition, the spring assembly 91 is moved rearwardly to in turn providefor a pivotal movement of the bell crank 98 in a clockwise directionabout its pivot I21, as viewed in Figs. 3 and 10, a movement of thelever 99 towards the right, as viewed in these same two figures, fromits position shown in Fig. 10 to its position shown in Fig. 3, and for apivotal movement of the T-member 89 in a counter-clockwise directionabout its pivot 88.

This pivotal movement of the T-member 89 provides for a concurrentmovement in opposite directions of the inner-adjacent ends of the driveshafts 46 and 46a due to the pivotal support of the upright arms I2 and12a on the common pivot I5 and the mounting of the inner ends of thedrive shafts 46 and 46a in the self-aligning bearings II and Na. Aspreviously mentioned the friction wheels I3 and 13a, when disengagedfrom the friction discs 66 and 66a, are in a clearance relation with thefriction discs, a distance on the order of about 1 1; of an inch. Due tothis relatively small clearance relation, the movement of the adjacentends of the drive shafts 46 and 46a, axially of the power shaft 51 isreadily accommodated by the self-aligning bearings II and Ila, and withthe inner end of the drive shaft 46a being moved forwardly and the innerend of the drive shaft 46 rearwardly in response to thecounter-clockwise movement of the T-lever 89. With this movement of theinner ends of the drive shafts 46 and 46a. in relatively reverseddirections, the friction wheel 13a is frictionally engaged with thefront disc 66a, and the friction wheel I3 with the rear friction disc66. As a result of this engagement of the friction wheels I3 and 13awith a corresponding disc 66 and 66a, the drive shafts 46 and 46a arerotated in the same direction to provide for F the travel of the tractorin a forward direction.

Further, and as will best appear from consideration of Fig. 13, thebearing pressure of the wheels I3 and 13a with the discs 66 and 66a ismaintained uniform by virtue of the compression of the spring H4 againstthe collar III as a result of the movement of the collar I I6 out ofengagement with the stop screws I I9 and toward the stop screws H6. Thespring H4 thus acts uniformly on both friction wheels I3 and 73a byvirtue of the connection of the upright arms I2 and 12a through theT-member 89.

To reverse the travel of the tractor, the shift lever 96 is moved fromits forward position, shown in Fig. 13, through its neutral position,shown in Fig. 14, and then rearwardly from its neutral position to itsreverse position, shown in Fig. 15, as defined by the engagement of thearm I0! with the stop 95. In this reverse position of the shift lever96, it will be noted that the pin I08 is again moved to an off-centerposition relative to the pin I02 so as to lock the shift lever 96against movement toward its neutral position. During the movement of thelever 96 from its neutral position to its reverse position, the springassembly 91 is moved forwardly, toward the front friction disc 66a,whereby the spring I I4 is compressed by the collar I II against thecollar H6. Further, the bell crank 98, pivoted lever 99, T- member 89and inner adjacent ends of the drive shafts 46 and 46a are reverselymoved, relative to their movement in response to the movement of theshift lever from a neutral position to its forward position, whereby thefriction wheel 13 is moved into engagement with the disc 66. Thefriction'wheels 13 and 13a. are thus reversed relative to theirdirection of rotation for a forward advanceof the tractor to in turnprovide for a reversed rotation of the drive shafts 46 and 46a.

Likewise with the spring II4 compressed against the collar I.I6, anymovement of the friction wheels 13 and 13a out of engagement with thediscs 66 and 66a is resisted by the pressure of the spring I14, whichfunctions to maintain the bearing pressure between the friction discsand the friction wheels uniform. This bearing pressure may be varied byadjustment of the bolt extension I23, with a corresponding neutralposition of the spring being obtained by adjustment of the nut I22.

The movement of the friction wheels 13 and 13a axially of theircorresponding drive shafts 46 and 46a to vary the speed of rotation ofthe drive shafts .46 and 46a for tractor operating and steering.purposes will now be described.

Tractor speed change and steering mechanism 'The speed change andsteering mechanism, embodied in the system of this invention, will bebest understood from a consideration of Figs. 3 and 4 taken inconnection with Figs. 5 and 6', which latter figures show the essentialelements in the speed change and steering mechanism.

A pair of actuating bars I4I and I42 (Figs. 3 and 4) are arranged inatransversely spaced relation .longitudinally of and spaced above theshiftable bar 83, with the rear ends I43 and I44 of the actuating barsI4I-and I42, respectively, terminating substantiallygat the rear end 84of the shiftable bar 83. The rear ends I43 and I44 of the actuating barsare of a flat construction and laterally inclined toward each other soas to be in an overlapping relation (Figs. 3 and 5). The assemblyrelation of the actuating bars I4I and I42 with their associatedfriction wheels 13 and 13a, respectively, is the same, so only theassembly of the actuating lever I4I with its friction wheel 13 will bereferred to in detail. Similar numerals will be used, therefore, todesignate like parts in these assemblies.

The rear end I43 of the actuating bar I4I is pivotally connected at I46with a rock arm I41 (Figs. 3, 4, 5 and 6) which is mounted on an uprightrock shaft I48. The rock shaft I48 has its upper end rotatably supportedin a top plate member I49, welded to the top frame IOI, while its lowerend is supported in a lower plate I5I secured to the rear connectingmember 56a. Adjacent its lower end, the rock shaft I48 carries a pair ofvertically spaced rock arms I52 the free ends of which are pivoted atI53 to one of the ends of connecting levers I54. The other ends of thelevers I54 are pivoted at I56 to a ring member I51 having inwardlyextended projections I58 receivable in an annular groove I59 formed inthe hub member 16 for the friction wheel 13. The rock arms I52, leversI54 and ring assembly I51 thus constitutes what might be termed aslidable yoke member relative to the hub 18. Thus, in response to apivotal movement of the rock arm I41, the free ends of the rock arms I52are moved in parallel arcuate paths which extend substantially axiallyof the drive shaft 46 to in turn provide for a movement of the frictionwheel 13 axially of the drive shaft 46.

The front end portions of the actuating bars I4I and I42 are formed withoppositely arranged.

rack sections I6I and 162, respectively, and are movably supported forlongitudinal movement in cooperating horizontally disposed U-shapeguides or brackets I63 and I64, also respectively, having the free endsof theirlegs in an overlapping relation whereby to form a guide sleeveof a substantially rectangular shape in transverse cross section (Figs.5 and '1).' The front end sections of the actuating bars I4I and I42 areenclosed within a square tubular'casing I68 which extends forwardly ofthe housing 41 at a position between the connecting member 52 and thetop frame IIJI (Figs. 1 and 5). A bracket I69 (Figs. 4 and 5),integrally formed at the lower rearend of the casing I68; is secured asby screws I1I to the connecting member 52, and an extension I12 for thetop wall I 13 of the casing I68 is secured to the top frame I8I. Formedin the casing top wall I13 (Figs. 5 and 6), isv a longitudinallyextended slot I14 which is closed by a pair'of sliding plates I16 and.I16a arranged at opposite sides of the top wall I13. Located between thesliding plates l16-and within the slot I14, but of a length less thanthe length of the slot I14, is a guide plate I11.

A sleeve bearing I18 (Figs. 5 and 7) is secured to and projects upwardlyfrom the upper slide plate I16 and rotatably supports a shaftassemblycomprising .a tubular shaft I19 and a solid shaft I8I rotatablymounted within the tubular shaft. The tubular. shaft I19 extends throughthe slide plates I16 and H611 and the guide plate I11 with its lower endI83 terminating within the U-shape brackets I 63 and I64. A pinion gearI84 mounted on the lower end of the shaft I19 is adapted for concurrentmeshing engagement with the rack sections I6I and. I62 of the actuatingbars I4I and I42, respectively.

The shaft I8Iv extends through the slide plates I16 and H611, the guideplate I11 and the brackets I63 and I64 soas to project within the casingI68 downwardly from the lower end of the tubular shaft I19. Mounted onthe shaft Isl, at a positionbelow the pinion gear I84, is a pinion gear186 whichis in meshed engagement with a rack member I81 secured to aside wall of the casing I68. As shown in Fig. 1,1the tubular orsteeringshaft. I19 is equipped with a large hand wheel I88'for turning purposes,while the solid or speed-change shaft I8I is equipped with a small handwheel I89 which is located above the hand wheel I88, with both of thehand wheels I88 and I89 being arranged forwardly of the tractor operatorseat 49 at a height conveniently accessible to the operator.

To steer the tractor through a relative change in speed of the tractionwheels 3| and 3Ia', the hand wheel I88, as viewed in Fig.6, is turned ina clockwise direction for steering to the'right, and in acounter-clockwise direction for steering to the left. Thus, assume theactuatingbars I4I andI42 and friction wheels 13 and 13a to be in theirrelative positions shown in full lines in Fig. 6. nFurther, let it beassumed that the friction wheels 13 and 13a are in their full-linepositions, as also shown in'Fig. 6, in which the wheel 13 isfrictionally engaged with the rear disc 66, and the wheel 13a with thefront disc 66a, so as to provide for a forward advance of the tractor.On rotation of the hand wheel I88 in a clockwise direction, as viewedinFig. 6, the pinion gear I84 acts upon the rack sections IIiI and I62such that the actuating bar I4Ifis moved forwardly, or upwardly, asviewed in Fig. 6, concurrently with: a movement of the actuating "barI42 rearwardly, or downwardly, as also viewed in Fig. 6. The forwardmovement of the actuating bar I4I provides for a pivotal movement of therock arm I41 associated therewith in a counter-clockwise direction, withthis movement in turn providing for a counter-clockwise. movement of therock arm I52 and an axial movement of the friction wheel 13 toward theleft, and transversely of thefriction disc 66 toward the outer peripherythereof. By virtue of this axial movement of th friction wheel 13 in adirection toward the outer periphery of the friction disc 56, the speedof rotation of the drive shaft 46, corresponding thereto, is increased.

Concurrently with the increase in speed of rotation of the frictionwheel 13, the rotational speed of the friction wheel 13a is reduced as aresult of the rearward movement of the actuating bar I42 and themovement of the rock arms I41 and I52 corresponding thereto in acounterclockwise direction, as viewed in Fig. 6, whereby to move thefriction wheel 13a inwardly toward the center of the friction disc 65a,with this movement resulting in a reduced rotational speed of thefrictional wheel 13a and in turn of the drive shaft 46a.

With the increase in rotational speed of the drive shaft 48 and thedecrease in rotational speed of the drive shaft 46a, the traction wheel3[ is driven faster than the traction wheel am so as to provide for aturning to the right of the tractor.

For a steering of the tractor to the left, the hand wheel I88 is turnedto the left or in a counter-clockwise direction, as viewed in Fig. 6,whereby the pinion gear I84, through the rack sections IGI and I62,moves the actuating rod I42 in a forward direction and the actuating rodMI in a rearward direction. This relative movement of the actuating rodsMI and I42, in the manner previously above described for a right turn ofthe tractor, provides for a concurrent movement of the friction wheels13 and 13a to the right, as viewed in Fig. 6, whereby the drive shaft46a is driven at a faster speed than the drive shaft 46. As a result,the traction wheel 3Ia is rotated at a speed faster than the tractionWheel 3I so that steering takes place to the left, or about the tractionwheel 3 I.

During the operation of the hand wheel I88 for tractor steeringpurposes, the steering shaft I19 and in turn the pinion gear I84 areheld against free movement longitudinally of the casing I68 by meansincluding a clamping screw IBI (Figs. 6 and 8) which has an enlargedshank portion I92 adapted for abutting engagement with the top side ofthe slide plate I18, and a shank portion I93 of a reduced sectionloosely extended through the slide plate I16 and guide plate I11 forthreadable engagement within the lower slide plate [16s. Thus, ontightening of the screw I9I, the plates I16 and I'IBa are moved intofrictional engagement with opposite sides of the casing top wall I13. Byvirtue of the assembly of the steering shaft I19 and speedchange shaft I8| within the sleeve hearing I 18 on the upper slide plate I16, thepinion gear I84 is frictionally held stationary relative to theactuating bars MI and I42. It is contemplated that this frictionalholding action be sufficient to prevent a free movement of the gear I84longitudinally of the casing I88 while permitting a manual movement ofthe gear longitudinally of the casing. In other words the shaft I19 and.gear I84 are manually movable to changed posi- -12 tions against thefrictional holding action of the side plates I16 and Ba.

In the event the friction wheels 13 and 13a are in either of theirextreme movedpositions transversely of the discs 66 and 68a, actuationof the steering wheel I88 in either direction will effect a transversemovement of only one of the wheels away from its extreme positiontoaccomplish' a desiredturn. This movement of only one of the wheelstakes place against the frictional holding of the slide plates by theclamp 38],. and is accomplished by the travel of the gear 584 along theactuating bar MI and I42 corresponding to the friction Wheel not beingmoved. Thus the actuating bar I4I and I42 corresponding to the frictionwheel 13 or 13a, which is not moved, remains stationary so as tofunction as a rack relative to the gear I84, whereby the gear me onlyactuates the actuating bar correspondingto the friction wheel beingmoved. As a result, the gear I84 and one of the actuating bars are movedlongitudinally relative to the casing 558. while the other actuating barremains stationary relative to the casing I68.

A change in the rotational speed of the drive shafts 45 and 45a, and inturn of their corresponding traction wheels SI and am, is accomplishedby rotation of the small hand wheel I89.

For an easier manipulation of the hand wheel I89, the clamping screw ISImay be loosened so as to provide for a free slidable movement of theplates I15, Ilfia and I11 longitudinally of the casing I68. Thus,referring to Fig. 6, assume the actuating bars I4I and 42 and thefriction wheels 13 and 13a to be in their relative positions, as shownin full lines. To increase the speed of rotation of the drive shafts 46and 46a, the hand wheel l8 9is turned in a clockwise direction, asviewed in Fig. 6. As a result of this rotation of the hand wheel I89 andspeed-change shaft ISI, the gear I is moved forwardly along the rack barI81. Since the rack sections IBI and 52 of the actuating bars MI andI42, respectively, are in continuous meshing engagement with the piniongear I84, the actuating rods are locked against relative movement andare movabletogether in a forward direction from their full-linepositions, shown in Fig. 6, to'their dotted-line positions, shown in thesame figure.

This concurrent forward movement of the actuating rods E48 and I42provides for a clockwise movement of the rock arm 352 corresponding tothe friction Wheel 13d and for a counter-clockwise movement of the rockarm I52, corresponding to the friction wheel 13, whereby the frictionwheels 13 and 351, are simultaneously moved in directions away from eachother, and toward, the outer peripheries of their respective discs 66and 66a. The rotaticnalspeeds of the drive shafts 4t and 46a, and inturn of the traction wheels 3| and 3m, are thus simultaneously increasedby like amounts. 1 f

To simultaneously reduce the rotational speeds of the drive shafts 4'6and 46a. by like amounts, the hand wheel 289 is rotated in acounter-clockwise direction, as viewed in Fig. 6, so as to provide for arearward movement of the actuating rods I4! and I42 and a simultaneousmovement of the friction wheels 13 and 13a inwardly toward each other.The desired speed of rotation of the drive shafts 45 and 46a is thenmaintained by merely tightening the clamping screw I9I Sharp turn orspinner mechanism Aturning movement of the tractor within a 13 distancedefined bythe transverse distance lie-- tween the traction wheels 3! and31a is accomplished by means including the pivoted upright arms 12 and72a (Figs. 9 and the T-member '89 and shiftable bar 83, previouslydescribed.

Pivoted at on the supporting plate 8i is an operating lever 202 whichextends laterally of the housing ll so as to project outwardly from theside thereof opposite *the shift lever 96. The inner end of theoperating lever 262 is pivoted at 293130 the shiftable'bar 83.

Prior to any manipulation of the lever 282 for turning the tractoraround within the width of its own tracks, .the shift-lever 96 is movedto its neutral position, shown in Fig. 10, whereby both of the frictionwheels [3 and i366 are out of frictional engagement With'the discs 66and 63a. On forward movement of the lever 202 from its fullline positionto its dotted-line position, shown in Fig. 10, the shiftable rod 83 .ismoved rearwardly from its full-line position to its dotted-lineposition, also shown in Fig. '10, with .the T-member 89 being movablewith the shiftable bar 83 to its dotted-line position, shown in the samefigure. As a result of the pivotal support of the upright arms T2 and72a on thecommon pivot 15, and the pivotal connection of the upper endsof these arms at 93 and 93a, respectively, with the cross arm 8! of .theT-member 89, :the inner-adjacent ends of the drive shafts-46 and Mia aresimultaneously moved rearwardly toward the rear friction disc 53 to inturn provide for the frictional engagement of the wheels T3 and 13a withthe disc 6%. With the wheels "53 and 73a in frictional engagement withthe common disc '65, the drive shafts 35 and 4.6a are rotated inrelatively reversed directions, so that the spinning or turning movementof the tractor within the width of its own tracks takes place in adirection towards the right, namely, the traction wheel 35 is advancedwhile the traction wheel 31a is reversed. By moving the lever .2192.rearwardly from its fullline position, shown in Fig. 10, thefrictionwheels "E3 and 13a are moved into frictional engagement with the frontdisc Eta to provide for a spinning movement of the tractor in adirection towards the left.

The system also includes the provision of means for independentlybraking the traction Wheels 3| and Zia to attaina complete stopping ofthe machine, and the utilization of the braking mechanism for steeringpurposes, in lieu of operating the hand wheel E83, whereby to increasethe overall flexibility of operation of the tractor.

Braking mechanism This braking mechanism includes a pair of equalizinglevers 22! and 221a (Figs. 3, .9 and 12) corresponding to the driveshafts 36 and 55a. Since each equalizing lever 22] and 22m is of a likeconstruction and similarly assembled in the system of this invention,only thelever 224 will be described in detail. As shown in Fig. 12, thelever 221 is of a substantially T-shape with the cross arm 222intermediate the ends thereof being formed with a central notch orrecess 223. Arranged at opposite sides of the central notch 223 is apair of oppositely arranged notches 22 i and 226 which are open toopposite sides of the cross arm 222.

The equalizing lever 22f has the cross arm 222 thereof positionable atthe rear end of the plate support 8i (Figs. 3 and 9) while the free end22'? of the leg section 228 thereof is arranged between the cross arm 9!of the T-member 89 and the latera] projectionist :ofx the'upright arm 12for pivotalconnectionwiththepivot. 93. The rear end of the supportingplate. 8] isprovidedwith an upciation with its=corresponding-drive shaft46 will be referred to in detail. 1

The cross arms 23-3 (Fig. 9) is provided at its opposite ends withdownwardly extended pins 235 and 235 which are loosely receivable in there versed notches 22-4 and 226, respectively, of the equalizing lever22!. "The leg portion 235 of the equalizing link- 23!, extends forwardlyover the supporting plate 8! for pivotal connection of its free end at2-31, withone-end of a lever 233, the opposite'endof which is pivoted at239 to a crank arm 2M rotatably supported in a bearing 2 52 whichissuitably securedto theconnecting member '52. The lever 238 is extendedtransversely of the housing 41, and in turn of the'tractor, and thebearing 24? extends longitudinally of the housing. A second crank arm243 connected on a shaft 244, which is "common to the crank arm 23?, ispivoted at 246 to the top end of an upright lever 26?, the lower end 'ofwhich is pivoted at 2&8 to a foot brake 'lever2'4'fl.

The brake lever 249 is mounted at its rear end on a shaft 251 (Figs. 2,3 and '17) extended transversely of the tractor and rotatably supportedin a bearing 250 carried'on the forward end of the longitudinal tubularmember 54 and in a bearing 252 which is carried on an, upright standard255 secured to the longitudinal frame member 2 i. A

rock arm 260, 'a't'the outerend of the shaft 2M, i

provided atits free end with a sleeve bearing 253 which receives in alost motion connection a rod 254 for operating a brake unit, indicatedgenerally as 256. The front end of the rod 254 carries adjusting nuts25'! which are arranged at opposite ends of the sleeve bearing 2 53.

The brake unit 25.6'comprises a brake drum 25% mounted on the driveshaft 46. A brake band 259, frictionally engageable with the brake drum'258, has its adjacent ends 261 'yieldably connected together through aspring connection 262, and its closed side 263 supported by springs 264from an upright standard 236 on the longitudinal frame member 2].Connecting links 261 have one of their ends pivoted at 268 to the brakeband 259 at positions spaced from the band ends 2% i, while theiropposite ends are connected through a common pivot 269 with the rear endof the connecting rod 254.

In the operation of the brake system it is contemplated that the driveshaft, corresponding to the brake lever to be operated, be substantiallyout of a driven relation with the power shaft 5? at the time brakingaction takes place on the drive shaft. In other words, the brake will beapplied on the drive shaft before power thereto is completely removed.Thus, for a, braking action on the drive shaft 4'6, assume that theshift lever 96 is in its position providing'for a forward advance of thetracton'as shown in Fig. '3, whereby the T-member89 is pivotal'ly movedto provide fora frictional engagement ofthe'wheel lSa with acoasss thedisc 66a, and of the wheel I3 with the disc 66. This position of theT-member 89 in Fig. 3 corresponds to its position shown in full lines inFig. 9. By virtue of the loose reception of the pins 234 and 235 withinthe notches 224 and 226, movement of the T-member 89 in response to amovement of the shift lever 96, takes place without effecting anymovement of the equalizing link 23L In other words, the pin and slotconnections, above described, provide for a lost-motion connectionbetween the equalizing lever 22I and the equalizing link 23L Ondepressing the brake lever 249, and referring to Fig. 9, the equalizinglink 23I is moved to its dotted-line position, shown in Fig. 9, by theaction of the levers 241 and 238, and cranks 24] and 243, the movedpositions of which are also shown in dotted lines in Fig. 9. On movementof the equalizing link 23I from its full-line position to itsdotted-line position, the pin 234 initially engages the bottom of therecess 224 whereby the equalizing lever 22I is moved forwardly, to inturn provide for a forward movement of the upright support 72, to aposition defined by the engagement of the pin 235 with the bottom of therecess 226. With both of the pins 234 and 235 in abutting engagementwith the bottom of their corresponding recesses 224 and 226, theequalizing link 23I is locked against further movement, with this lockedposition defining a neutral position of the friction wheel I3 relativeto the discs 66 and 66a so as to cut off the supply of any power to thedrive shaft 46.

Just as the pressure of the friction wheel I3 on the disc 66 is beingreleased by the depression of the brake lever 249, the pressure of thebrake band 259 is applied to the brake drum 258 so that when thefriction wheel I3 has been brought to its neutral position the brake isfully applied. The drive shaft 45, and in turn its correspondingfriction wheel 3I, is thus braked against further rotation. It will beappreciated that as the brake is applied to the traction wheel SI, thetraction wheel 3Ia will continue to have power supplied thereto, so thatunless the brake mechanisms corresponding to the traction wheels 3| and3 Id are simultaneously applied to the drive shafts 46 and 48, a turningmovement of the tractor in the direction of the traction wheel beingbraked will take place.

On a release of the brake lever 249 the T- member 89 is returned to itsposition providing fora forward advance of the tractor as a result ofthe pressure applied thereon by the spring I I4 of the spring connection97. Conversely, it will be appreciated that the movement of the T-member89 out of what might be termed its normal position and providing for thedisengagement of the friction wheel 13 from the friction disc 66, inresponse to the actuation of the brake lever 249, takes place againstthe pressure of the spring H4.

Summary From a consideration of the above description, it is seen thatthe invention provides a combination power transmission and steeringsystem for a three wheel tractor that provides for what might be calleda finger-tip control of the tractor by the operator, and for a completemaneuverability of the tractor to readily accomplish all farmingoperations. As best appears from a consideration of Figs. 1 and 2, thehousing 41 for the system is located adjacent the front end of thetractor, and the tractor operators seat 49 is carried on the housingcover 48, so that the ground immediately ahead of the tractor is in fullview of the tractor operator. Thus, for example, a cultivator implement,indicated generally at 210 in Figs. 1 and 2, and movably mounted throughmeans including links 2' and 2'12 to the tractor frame 20 has all of itsshovels 213 in the full vision of the tractor operator. Further, thehand-operated levers 214 for raising and lowering the cultivator 210 canbe positioned for ready manipulation by the operator.

As a result of the full maneuverability of the tractor, and the completevisibility of the farm implement by the tractor operator, the cultivator210 is manipulated as a self-propelled unit capable of following any rowcontour and able to work in very close quarters. Further, the system ofthis invention eliminates the use of any differential or clutchmechanisms, and accomplishes a forward or reverse advance of the tractorsmoothly and quickly.

Also, the tractor is readily adapted to be operated with equal facilityin either a forward or a reverse direction, depending upon the use ofthe tractor for either pushing or pulling purposes. Thus for instance,in the event the cultivator is replaced by a plow (not shown) which isto be pulled, rather than pushed, the operators seat 43 may be assembledon a forward extension (not shown) of the casing I68 so as to face thecastor wheel 32. Then by merely pivotally connecting the rear end I43 ofthe actuating rod [M (Fig. 3) with the rock arm I41 corresponding to thedrive shaft 46a, and pivotally connecting the rear end I44 of theactuating rod I42 with the rock arm I41 corresponding to the drive shaft46, the system of this invention is operable to provide for themanipulation of the tractor, with the castor wheel 32 utilized as afront wheel, in all respects similar to its operation, described above,with the castor wheel 32 utilized as a rear wheel.

Although the invention has been described with respect to a preferredembodiment thereof, it is to be understood that it is not to be solimited since changes and modifications can be made therein which arewithin the full intended scope of this invention, as defined by theappended claims.

I claim:

1. A power transmission system comprising, a power shaft having a pairof spaced friction discs mounted thereon, a pair of co-axial driveshafts normal to said power shaft arranged between said discs, meanssupporting said drive shafts such that their adjacent ends are movableaxially of said power shaft, a friction wheel mounted on each of saiddrive shafts for movement axially thereof, with each friction wheelbeing adapted to frictionally engage one or the other of said frictiondiscs, means for axially moving said friction wheels including a pair oflink systems corresponding to said wheels, with each link system havingan operating lever extended axially of said power shaft at a positionbetween said wheels, means movably supporting said levers forlongitudinal movement, means connecting said levers for concurrent andrelative longitudinal movement to provide for a concurrent and relativemovement of said wheels axially of said drive shafts, a first actuatingmeans for concurrently moving said operating levers, and a secondactuating means for relatively moving said operating levers.

2. A power transmission system comprising, a power shaft, a pair ofspaced friction discs mounted on said power shaft, a pair of driveshafts arranged between said discs at opposite sides of and normal tosaid power shaft, a friction wheel mounted on each of said drive shaftsfor rotational movement therewith and axial movement thereon, meanssupporting said drive shafts for movement toward and away from saidfriction discs to provide for the frictional engagement of a frictionwheel with one of said friction discs, means for axially moving eachfriction wheel including a bell crank, means movably connecting one armof said bell crank with said friction wheel, an actuating lever movablyconnected with the other arm of said bell crank, with the bell crank andactuating lever for each friction wheel being relatively assembled suchthat the actuating levers are arranged in a substantially parallelrelation adjacent to each other, gear rack portions oppositely arrangedon adjacent sides of said levers, means including a rotatable gearelement concurrently engageable with said rack portions for moving saidlevers relative to each other whereby the friction wheels correspondingthereto are moved axially of their associated drive shafts to relativelyvary the speeds thereof, and means for moving said actuating leverstogether as a unit to axially move said friction wheel to vary therotational speeds of said drive shafts by like amounts.

3. A power transmission system comprising, a power shaft, a pair ofco-axial drive shafts normal to said power shaft and arranged atopposite sides of said power shaft, a pair of friction discs on saidpower shaft arranged at opposite sides of said drive shafts, a frictionwheel on each drive shaft for frictionally engaging a friction disc,means providing for the frictional engagement and disengagement of saidfriction wheels with said friction discs, means movably supporting eachfriction wheel for movement axially of a corresponding drive shaft, apair of independent means for axially moving said friction wheels eachof which includes an actuating member and a lever system, means movablyconnecting a lever system between a friction wheel and an actuatingmember such that the lever systems are reversely moved in response to amovement of said actuating members in the same direction, with saidactuating members being arranged in a spaced parallel relation, meanssupporting said actuating members for longitudinal movement, oppositelyarranged rack portions on said actuating members, a gear common to saidrack portions, a tubular shaft for said gear projected outwardly fromsaid supporting means, a rack member fixed on said supporting means andextended longitudinally of said actuating members, a second gearengageable with said rack member, a shaft for said second gearpositioned within said tubular shaft, an adjustable member mounted onsaid supporting means for movement longitudinally of said actuatingmembers, with said gear shafts being carried on said adjustable member,said actuating members on rotation of said tubular shaft, being moved inopposite directions whereby to axially move said wheels in oppositedirections to relatively vary the rotational speeds of said driveshafts, and said actuating members and adjustable member, on rotation ofsaid inner shaft, being moved in the same direction whereby to axiallymove said wheel in opposite directions to vary the rotational speeds ofsaid drive shafts by like amounts.

4. A power transmission system including a power shaft, a pair ofcoaxial drive shafts arranged at opposite sides of said power shaft, apair of friction discs on said power shaft arranged at opposite sides ofsaid drive shafts, a friction wheel on each of said drive shaftsfrictionally engageable with one or the other of said friction discs,means supporting said drive shafts for movement axially of said powershaft to provide for the engagement and disengagement of said wheelswith said discs, a lever system including a rockable member forconcurrently moving said Wheels into and out of frictional engagementwith corresponding ones of said friction discs, with said wheels beingout of frictional engagement with said discs at one moved position ofsaid rockable member, means for yieldably holding said rockable memberin said one moved position therefor, and means, when said rockablemember is in said one moved position therefor, for moving said leversystem and rockable member as a unit to provide for the movement of saidwheels into frictional engagement with only one of said discs.

5. A power transmission system including a power shaft, a pair ofdriveshafts normal to said power shaft and arranged at opposite sides ofsaid power shaft, a pair of friction discs mounted on said power shaft,friction wheels mounted on the adjacent ends of said drive shafts, meanssupporting said drive shafts such that the adjacent ends thereof aremovable axially of said power shaft to provide for the frictionalengagement and disengagement of said wheels with said discs, a firstmeans for concurrently moving said adjacent shaft ends in oppositedirections so that each of said wheels is in frictional engagement witha corresponding disc whereby said drive shafts are rotated in the samedirection, means for yieldably holding said first means in a position atwhich said wheels are disengaged from said discs, and a second means,when said wheels are in frictionally disengaged positions, for movingsaid first means as a unit against the action of said yieldable mean toprovide for the concurrent movement of said adjacent shaft ends in thesame direction whereby to frictionally engage said wheels with only oneof said discs so that said drive shafts are rotated in relativelyreversed directions.

UMMO F. LUEBBEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

